The Obama administration will press Congress to allocate a coveted block of wireless telecommunications airwaves for the building of a nationwide emergency communications network, administration officials said, a reversal that is likely to cement support for an issue that has been the subject of disputes since Sept. 11, 2001.

Ever since the attacks exposed the inability of fire, police and rescue departments to talk to one another via radio in an emergency, public safety officials have pushed for the allocation of additional airwaves, also known as spectrum, for their dedicated use. But Congress had mandated that the wireless spectrum at issue — a prime block of airwaves known as D Block — be auctioned off to a commercial wireless company, which would raise money that could then be used to help build a public safety network. Both the Bush and Obama administrations had supported auctioning the spectrum, as had the Federal Communications Commission. Last June, the FCC published a white paper saying that a better public safety communications network could be constructed at lower cost by using airwaves already dedicated to public safety, supplemented by the right to essentially take over commercial networks in an emergency. After nine months of intense lobbying by public safety officials, senior administration officials informed public safety leaders shortly before the State of the Union address that President Obama would support their cause. How the reallocation will be paid for remains an issue, because the auction of D Block had been expected to raise more than $3 billion. Obama administration officials said they believed that their broader plan to conduct auctions of other spectrum, including unused airwaves voluntarily given up by broadcasters, will raise the extra money required to prevent the D Block allocation from increasing the federal deficit.